pytest plugin to check source code with pyflakes

pyflakes, pytest, python
pip install pytest-flakes==4.0.3



py.test plugin for efficiently checking python source with pyflakes.


install via:

pip install pytest-flakes

if you then type:

py.test --flakes

every file ending in .py will be discovered and run through pyflakes, starting from the command line arguments.

Simple usage example

Consider you have this code:

# content of

import os
from os.path import *

def some_function():

Running it with pytest-flakes installed shows two issues:

$ py.test -q --flakes
================================= FAILURES =================================
______________________________ pyflakes-check ______________________________
/tmp/doc-exec-685/ UnusedImport
'os' imported but unused
/tmp/doc-exec-685/ ImportStarUsed
'from os.path import *' used; unable to detect undefined names
1 failed in 0.00 seconds

These are only two of the many issues that pytest-flakes can find.

Configuring pyflakes options per project and file

You may configure pyflakes-checking options for your project by adding an flakes-ignore entry to your setup.cfg or pytest.ini file like this:

# content of setup.cfg
flakes-ignore = ImportStarUsed

This would globally prevent complaints about star imports. Rerunning with the above example will now look better:

$ py.test -q --flakes
================================= FAILURES =================================
_________________ pyflakes-check(ignoring ImportStarUsed) __________________
/tmp/doc-exec-685/ UnusedImport
'os' imported but unused
1 failed in 0.00 seconds

But of course we still would want to delete the import os line to have a clean pass.

If you have some files where you want to specifically ignore some errors or warnings you can start a flakes-ignore line with a glob-pattern and a space-separated list of codes:

# content of setup.cfg
flakes-ignore =
    *.py UnusedImport
    doc/ ALL

Ignoring certain lines in files

You can ignore errors per line by appending special comments to them like this:

import sys # noqa
app # pragma: no flakes

Running pyflakes checks and no other tests

You can restrict your test run to only perform "flakes" tests and not any other tests by typing:

py.test --flakes -m flakes

This will only run tests that are marked with the "flakes" keyword which is added for the flakes test items added by this plugin.

If you are using pytest < 2.4, then use the following invocation to the same effect:

py.test --flakes -k flakes


The repository of this plugin is at

For more info on py.test see

The code is partially based on Ronny Pfannschmidt's pytest-codecheckers plugin and Holger Krekel's pytest-pep8.


4.0.3 - 2020-11-27

  • Future proof some code against future versions of pytest. [RonnyPfannschmidt]

4.0.2 - 2020-09-18

  • Fix calling pytest --flakes directly on an file. [akeeman]

4.0.1 - 2020-07-28

  • Maintenance of pytest-flakes has moved from fschulze to asmeurer. The repo for pytest-flakes is now at
  • Fix test failures. [asmeurer]
  • Fix deprecation warnings from pytest. [asmeurer]
  • Fix invalid escape sequences. [akeeman]

4.0.0 - 2018-08-01

  • Require pytest >= 2.8.0 and remove pytest-cache requirement. Cache is included in pytest since that version. [smarlowucf (Sean Marlow)]

3.0.2 - 2018-05-16

  • Fix typo in name of flakes marker. [fschulze]

3.0.1 - 2018-05-16

  • Always register flakes marker, not only when the --flakes option is used. [fschulze]

3.0.0 - 2018-05-16

  • Drop support for Python 3.3. It still works so far, but isn't tested anymore. [fschulze]
  • Add flakes marker required since pytest 3.1. [fschulze]
  • Use pyflakes.api.isPythonFile to detect Python files. This might test more files than before and thus could cause previously uncaught failures. [asmeurer (Aaron Meurer)]

2.0.0 - 2017-05-12

  • Dropped support/testing for Python 2.5, 2.6, 3.2. [fschulze]
  • Added testing for Python 3.6. [fschulze]
  • Fixed some packaging and metadata errors. [fladi (Michael Fladischer), fschulze]

1.0.1 - 2015-09-17

  • Compatibility with upcoming pytest. [RonnyPfannschmidt (Ronny Pfannschmidt)]

1.0.0 - 2015-05-01

  • Fix issue #6 - support PEP263 for source file encoding. [The-Compiler (Florian Bruhin), fschulze]
  • Clarified license to be MIT like pytest-pep8 from which this is derived. [fschulze]

0.2 - 2013-02-11

  • Adapt to pytest-2.4.2 using add_marker() API. [fschulze, hpk42 (Holger Krekel)]
  • Allow errors to be skipped per line by appending # noqa or # pragma: no flakes [fschulze, silviot (Silvio Tomatis)]
  • Python 3.x compatibility. [fschulze, encukou (Petr Viktorin)]

0.1 - 2013-02-04

  • Initial release. [fschulze (Florian Schulze)]